The present invention relates generally to the field of threaded fasteners.
A study of the prior art patents reveals that a formidable amount of time and attention has been directed to the improvements of such design features, for example, as would facilitate forging operations during fabrications, the use of elements to break up the drilling chips, as well as others, which would and have undoubtedly contributed to the advancement of the art as it relates to the field of self-drilling screws.
We have discovered, however, that the prior developments have noticeably overlooked or neglected to consider the deleterious effects of drag or friction inherent in the conventional self-drilling screws.
In the present invention, we have therefore provided a unique arrangement of the cutting edges in relation to angularly extending associated relief surfaces such that the friction drag, heating, work-hardening and other inherent undesirable characteristics of the conventionally available self-threading screws will be materially reduced, and that as a result the selfthreading screws constructed in accordance with the features of our present invention will have improved operating characteristics.